Here's what we know regarding who did what so far, as well as some guesses:
- Namiki did seven tracks for the game, according to his old website. I'll ask him which ones at a later date, but to me Sonic Barrage, Emiya, and Win definitely sound like him, maybe Opening, VS, Continue and Game Over too.
- Abe told me he did the Crimson City arrangement as well as Next Stage/Map. He recalls doing more tracks but thinks that they might've went unused. Excalibur and maybe Event Serious sound like they could be him as well though, and he doesn't seem to rule out doing any others, just that those two tracks are definitely his work.
- Kaneda QRT'd 140VGM's post of Ending B. He found it nostalgic and said that the whistling sound is influenced by Unresolved Cases. I later asked him which tracks he did, and he also recalled doing Character Select, Colliding Spirits and Newcomer, and said his memory is hazy so he didn't rule out doing others as well.
- Kudo told me he didn't have the data and felt it was risky to disclose non-public information. I don't think there's any NDA in place and others have freely spoken about their contributions to Eighting games, though I understand his vigilance. Last Battle and Event Strain sound the most like his work, they have that prog rock feel.
In short, the following are confirmed:
Some great music here - what a pity that it never got a soundtrack release, and likely never will. I'll try and ask some of the others in the future too.